Xerographic reproducing apparatus



y 5, 1964 w. J. BURRIS EI'AL 3,131,617

WOGRAPHIC REPRODUCING APPARATUS 14 Sheets-Sheet 1 Filed Oct. 6. 1960INVENTOR. WILLIAM J. BURRIS JOSEPH J. comcm m BY RICHARD EJ'IAYFORD cmuss L.HUBER y' wflmmfr M y 1 w. J. BURRIS ETAL 3,131,617

XEROGRAPHIC REPRODUCING APPARATUS Filed Oct. 6. 1960 14 Sheets-Sheet 2mmvron. WILLIAM J. auams JOSEPH J. CODICHINI BY RICHARD E. HAYFORDCHARLES Luuasn 2-! A7TORNEK FIG? y 5, 1954 w. J: BURRIS ETAL 3;l31,6l7

xmqcmrmc Rmzowcmc APPARATUS Filed Oct. 6. 1960 14 Sheets-Sheet 3 WILLIAMJ. BURRIS BY JOSEPH J. CODICHIN!- RlCHARD E HAYFORD CHARLES L- HUBER 3964 w. J. BURRIS ET-AL 3,131,617

XEROGRAPHIC REPRODUCING APPARATUS 14 Sheets-Sheet 4 Filed Oct. 6, 1960INVENTOR. WILLIAM J. BURRIS JOSEPH J. CODICHINI BY RICHARD a HAYFORDCHARLES L. HUBER "M ATTORNEY y 5, 1964 w. J. BURRIS ETAL 3,131,617

XEROGRAPHIC REPRODUCING APPARATUS Filed on. s. 1960 14 Sheets-Sheet 5INVENTOR.

5 WILLIAM J. BURRIS JOSEPH J. CODICHINI RICHARD E. HAYEORD CHARLES L.HUBER 114 4/ ATTORNEY May 5, 1964 W. J. BURRIS ETAL XEROGRAPHICREPRODUCING APPARATUS 14 Sheew-Sheet 6 Filed Oct. 6, 1960 INVENTOR.WILLIAM J. BURRIS BY JOSEPH J. CODlCHINI RICHARD E. HAYFORD CHARLES L.HUBER 2 14M ATTORNEY y 1964 w J. BURRIS E TAL 3,131,617

XERQGRAPHIC REPRODUCING APPARATUS Filed 00t- 6, 1960 l4 Sheets-Sheet 7mmvrozz. WILLIAM J. BURRIS FIG. 8 BY JOSEPH J. coma-um RICHARD E.HAYFORD CHARLES L. HUBER Z411 ATTORNEY May 5, 1964 w.'J.BuRR1s ETALXEROGRAPHIC REPRODUCING APPARATUS l4 Sheets-Sheet 11 Filed Oct. 6, 1960IN 1 1 1H h y 5, 1964 .J. BURRIS ETAL 3,131,617

XEROGRAPHIC REPRODUCING APPARATUS 14 Sheets-Sheet 12 Filed Oct. 6. 19603 6m ww Q58 om w umnow m: or.

1964 w. J. BURRIS ETAL 3,131,617

XEROGRAPHIC REPRODUCING APPARQATUS Filed Oct. 6, 1960 14 Sheets-Sheet 13R 0" POWER OFF STAND BY 50 SEC STAND a! PRINT OFF RUN REPEAT TIME 0-40SEC. UNTlL] TIME IN SEQONDS Pam, OFF

SOL-l SOL-ll SV-IZ SOL-l SOL-l4 SV-l5 SV-IS SV-l? FILAMENT ONLY RESETTIME THERMOSTAT CONTROL REDUCE TORQUE REDUCE PREssuRE-------- rowanAPPLIED PULSE RATE INVENTOR.

(BPULSES PER secoup WILLIAM J. BURRIS 4 ON, 4 OFF) BY JOSEPH J.CODICHINI RICHARD E. HAYFORD CHARLES L. HUBER ATTORNEY United StatesPatent XERGGRAPHIC REPRDDUCHJG APPARATUS William James Burris, Warsaw,Joseph J. Codichini, Fair- 1 m, Richard E. Hayford, Pittsford, andCharles L.

HubenByron, N.Y., assignors to Xerox Corporation,

a corporation of New York Filed Oct. 6, 1966, Ser. No. 66,915 4 Claims.(Cl. 95-117) This invention relates to xerography and, in particular, toan improved xerographic reproducing apparatus.

More specifically, the invention relates to an improved automaticxerographic contact printer for use in producingxerographiccontinuous-tone reproductions from photographic negatives, negative orpositive transparencies, .by contact printing.

Continuous photographic printers of the type adapted to continuouslyfeed a negative film strip and a strip of sensitized printing paper inintimate contact with each other past a printing gate to expose thepaper to light passing through the negative to produce a latent imagethereon, which upon development by the usual photographic developingprocess to produce a print, are well known and in wide commercial use.However, in many --applications it is impractical to use thesephotographic contact printers since the usual chemical processes andcycle in making contact prints on roll photographic paper are timeconsuming and of course require the use of special chemicals andsensitized paper.

It is, therefore, the principal object of this invention to irnprovexerographic reproducing apparatus for making continuous-tonereproductions through contact exposure to a continuous strip ofphotographic film.

Another object of this invention is to improve Xerographic reproducingapparatus so that rapid modifications of contrast and exposure can bemade continuously while the machine is in operation to obtaincontinuous-tone prints having any degree of contrast as desired.

These and other objects of the invention are attained by means of acharging device, a contact exposure mechanism includ nga film transportsystem, a developer mechanism, a transfer device, a paper transportsystem and ifuser mechanism, and a drum cleaner, all operativelypositioned around a rotatably journaled xerographic drum.

For a better understanding of the invention as well as other objects andfeatures thereof, reference is had to the following detailed descriptionof the invention to be readin connection withthe accompanying drawings,wherein:

FIG. ,1 illustrates schematically a preferred embodi ment of a,xerographic reproducing apparatus of the invention;

FIG. 2 is a front View of the xerographic reproducing apparatus with itsenclosure covers removed;

FIG. 3 is aleft-hand side view of the xerographic reproducing apparatus;

FIG. 4 isaifront view of the film handling and projection apparatus ofthe machine;

FIG. 5 is a right-hand side view of the and projection apparatus;

FIG. 6 is a rear view of the development apparatus of the machine withparts broken away to show details of construction;

FIG. 7 is a sectional view of the development apparatus taken along line7-7 of FIG. 6;

FIG; 7a is an enlarged sectional View of support elements for thetransverse rails supporting the develop ment electrodes;

FIG. 8 is an enlarged section-a1 view of a development electrode driveclutch;

FIG. 9 is .a schematic pneumatic circuit diagram of film handling3,131,617 Patented May 5 1964 ICC a development electrode and elementscooperating therewith in position to effect development;

FIG. 9a is a schematic pneumatic circuit diagram il lustrating adevelopment electrode and elements cooperating therewith in positiontoefiect purging;

FIG. 10 is a schematic pneumatic circuit diagram of the xerographicreproducing apparatus;

FIGS. 11, 11a, 'llb, and llc are schematic electrical Wiring diagrams ofthe machine; and

.FIGS. 12 and 12a are sequence of operation charts of the machine.

Referring now to FIG. 1 there issho'wn schematically a preferredembodiment of a Xerographic reproducing apparatus adapted for continuousand automatic operation. The Xerograph-ic reproducing apparatus shown isa continuouscontact printer and processor of one-to-one size prints fromphotographic serial negatives by contact printing of the film.

As shown, the xerographic apparatus comprises a xerographic plateincluding a photoconductive layer or lightreceiving surface on aconductive backing and formed in the shape or" a drum, which isjournaled to rotate in the direction indicated by the arrow to cause thedrum surface sequentially to pass a plurality of xerographic processingstations.

For the purpose of the present disclosure, the several xerographicprocessing stations in the path of movement of the drum surface may bedescribed functionally, as follows:

A charging station, at which a uniform electrostatic charge is depositedon the photoconductive layer of the xerographic drum;

An exposure station, at which a light or radiation pattern of copy to bereproduced is projected onto the drum surface to dissipate the drumcharge in the exposed areas thereof and thereby form a latentelectrostatic image of the copy to be reproduced;

A developing station, at which a developing material is directed overthe drum surface, whereby the developing material adheres to theelectrostatic latent image to form a Xerographic powder image in theconfiguration of the copy being reproduced;

A transfer station, at which the Xerographic powder image is transferredfrom the drum surface to a transfer or support material; and,

A drum cleaning and discharge station, at which the drum surface isbrushed to remove residual particles of developing material remainingthereon after image transfer, and at which the drum surface is exposedto a rela tively bright light source to efiect substantially completedischarge of any residual electrostatic charge remaining thereon.

Referring now to FIGS. 1 and 2, there is shown the general arrangementof the xerographic apparatus. As shown, there is provided a frame forsupporting the components of the apparatus formed by a base plate 3 anduprights 4 connected together and maintained rigidly in spaced relationto each other by suitable tie plates, such as 5 and 6. A mounting plate3 is supported by the tie plates intermediate the outer sides of theframe.

The xerographic drum 10 is mounted on horizontal driven drum shaft 1 1,the drum being positioned on the front of plate 8 as seen in FIG. 1. Todrive the drum there is provided, as shown in FIG. 7, a drum drive motorMOT-9 secured by motor bracket 12. to plate 8. The shaft ot motorMOT-9is coupled to the input shaft of gear reducer 13 While the output shaftof the gear redwcer is coupled to the end of drum shaft 11 which isjournaled bearing sleeve 14 connected at opposite ends to plate 8 andthe gear reducer 13, the latter being mounted on horizontal frameelement 7 of the frame.

At the charging station there is positioned a corona generating device15 which includes a corona discharge array of one or more coronadischarge electrodes that extend transversely across the drum surfaceand are energized from a high potential source, the electrodes beingsubstantially enclosed within a shielding member. The potential appliedto the dnum depends upon the particular contrast desired in the finishedreproductions; i.e., high contrast reproductions require higher initialdrum potentials, whereas low contrast require lower initial drumpotentials. Although any one of a number of types of corona generatingdevices may be used, a scorotron and its electrical control circuit,described in detail hereinafter, of the type disclosed in copendingCodichini application, Serial No. 19,846, filed on April 4, 1960, nowPatent 3,062,956, is used for charging the xerographic plate. 7

Positioned next adjacent to the corona generating device is aconventional rotating vane type electrometer 16 driven by a motor MOT-8used to measure the potential applied to the plate by the coronagenerating device. The corona generating device 15 and the electrometer1-6 are secured to brackets 17 and 18, respectively connected to plate 8and are connected to an electrical circuitas shown in FIGS. 11, 11a, andllb.

Exposure Mechanism Next subsequent thereto in the path of motion of thexerographic drum is the exposure station. As shown, a contact exposuremechanism, constructed in accordance with the invention, is used toexpose the image from a photographic serial negative ontothe drum.

Asshown in particular in FIGS. 4 and 5, the film 21 is threaded from asupply roll 22 over idler rolls 23 and 24 then between the drum 1t and arubber pressure roll 25, a second idler roll 23 positioned adjacent thedrum, over an idler 26 and finally onto the rewind spool 27.

The supply roll 22, removably journaled at one end in a conventionalhinged film gate assembly 28 connected to the front of mounting plate 8and in bearing support 31 connected to the back side of the mountingplate, has a gear 32 connected thereto that meshes with gear 33 on thehysteresis brake SB4, of conventional design, secured to plate 8 wherebya braking force is applied to the supply roll to prevent it fromrotating freely. The power to the brake S B-d is controlled by autotransformer T3 directly geared to a follower or dancer roll 35 whichrides on the film on the supply roll, the follower being forced intocontact with the film by spring 36 connected at one the film is requiredto unwind the roll of film.

Like the supply roll, the rewind spool 27 is also journaled in a filmgate assembly 28 and a bearing bracket 31 To drive the rewind spool,there is provided a gear head motor MOT-2 connected by coupling 37 tothe input shaft of hysteresis clutch SC-S. Theoutput shaft of thisclutch has a gear 33 which drives the gear 32 connected to the rewindspool. Both the bearing mounts 41 in which the shafts of the clutch arejournaled and the motor MOT2 are secured to a suitable sub-base plate 42connected to the frame of the machine.

The torque applied to the rewind spool is a function of the powerapplied to the hysteresis clutch SC-5. The power to the clutch 56-5 iscontrolled by a Variac T d which is regulated by a spring 36 biasedfollower or dancer roll 35 sensing the roll diameter of the film on therewind spool; With this arrangement, the film web is subjected to theconstant force required to unwind the film from the supply spool and tothe constant force being supplied by the rewind spool. These forces arebalanced so that when the drum is not'in motion, the film is stationary.The film sandwiched between the drum and the pressure sipate heatgenerated by the projection lamp.

roll 25 is in friction contact with the drum to be advanced by the drum,synchronous motion of the film and drum thus being assured. Theunbalancing force supplied by the drum drive can be relatively small inmagnitude and yet the rewind spool is tightly wound with film and thefilm is maintained in constant tension to ensure good contact with thedrum.

Idler ro'lls 23 and idler 26 are each jour-naled in suitable bearings 43connected directly to mounting plate 8. However, to permit the pressureroll 25 to be brought into contact with the surface of the drum with thefilm sandwiched therebetween, or out of contact with the drum to permitthreading of therebetween, there is provided a roller carriage 44movably supported on carriage rail 45 connected at opposite ends to railbrackets 46 secured to the back side or right hand side of mountingplate 8, as seen in FIG. 5.

The pressure roll 25 and idler roll 24 extend through suitably elongatedslots 4? in the mounting plate 8 and are journaled at one end inbearings 47 secured to the roller carriage for movement therewith.

' For moving roller carriage 44 and therefore idler roll .24- andpressure roll 25 from a first position in which the pressure roll is outof contact with the drum to a second position in which the pressure rollis in contact with the drum with film 21 sandwiched therebetween, thereis mounted on the back side of mounting plate 8 an air cylinder 43having its plunger 51 connected by pin 52 to the top of the rollercarriage. As shown, the roller carriage is supported and guided near itstop by carriage rail 45, while its lower portion rides on carriage guide53 suitably secured to mounting plate 8.

Movement of the roller carriage to the leit, as seen in FIG. 4, islimited by adjustable carriage stop 54 secured to the mounting plate 8.

The operation of the air cylinder 48 connected to a pneumatic circuit,as shown in FIG. 10, is controlled by solenoid valve SV-6 connected tomounting plate 8, as seen in FIG. 5. a

Exposure of the drum to the image carried by the filth is made by aprojection lamp LMP-2 positioned within a suitable lamp housing 61, thelight being projected through suitable slots in the walls of the lamphousing then through the slotted projection tube 62 which is con-.nected at one end to the lamp housing and at its opposite end tobracket 63 secured to plate 8. The intensity of within the lamp housing.A beam splitting mechanism 67 is arranged within the projection tube sothat a certain portion of the light that passes through the circulardensity wedge is reflected up through a suitable slot in the upper wallof the projection tube 62 and directed through the film 21 passingthereover and then onto a photovaltaic cell PC-l mounted on bracket 68adjacent to the projection'tube and over the film. The photovoltaic cellis used to measure the average density of the negative and to record thefilm density on meter M6 as shown schematically in FIG. 11a.

, The operator can vary the amount of light to be projected through thefilm to compensate for variations in the density of the film by turningan exposure control knob 71 positioned on the control panel at the frontexterio-r of the machine. The control'knob '71'is connected is shown) tothe shaft 65 for rotating the density wedge 64 to regulate the amount oflight striking the drum surface through the film. A conventional motorMOT-7 driven blower '73 is connected to the lamp housing to disDevelopment System The electrostatic latent image produced by exposureof the charged drum to an image pattern of light is deform of theelectrostatic latent image thereon.

veloped with charged powder which, under the influence of electrostaticforces, deposits on the drum taking the In the development system of theapparatus, the xerographic plate passes over development electrodes,each having a slot therein from which an aerosol of charged developmentpowder is directed into a development zone defined as the spacebetweenxerographic drum and the development electrodes. The aerosol ofdeveloper powder, or powder cloud as it is generally referred to, isproduced in a disc generator in which an air stream raises a cloud ofdeveloper powder from a powder-covered revolving disc. A fine tubelocated in the development electrode charges the powdertriboelectrically by the impact of particles against the wall as the airstream carrying the powder moves through it in turbulent fiow.

In the apparatus disclosed, development of the electrostatic latentimage on the Xerographic plate is accomplished by five identicaldevelopment electrodes E-1, E-Z, E-3, 13-4 and E-S of the type disclosedin copending Hayford et al. application Serial No. 725,558, filed April1, 1958, now Patent 2,965,069, the development electrodes being formedto match the contour of the drum.

Since the five development electrodes and the elements associatedtherewith are identical to each other except for their mountingpositions, resulting in minor structural modifications to permit theirmounting in these positions, it is deemed necessary to describe indetail only one development electrode and its associated elements.

As shown, each development electrode is formed of electricallyconductive material to conform to the contour of the drum. As seen inFIG. '6, each development electrode contains an entrance slot 101directed to oppose the rotation of the drum through which the chargeddeveloping material is directed into the developing zone. The entranceslot extends transversely of the development electrode but terminatesinside the margin of the electrode so that the developing material isretained within the development zone, each development electrode beingwide enough, so that the entrance slots extend substantially the fullwidth of the drum.

Mounted within each development electrode is a ceramic needle 162, shownschematically in FIGS. 9, 9a, and

*10, of the type disclosed in Hayford Patent 2,859,129

issued November 4, 1958, for charging the developer materialtriboelectrically as it passes therethrough. Each entrance slot isconnected by a suitable powder cloud line to a source of powdereddeveloper material or to a clean air line controlled by a suitableelectrode purge valve mounted on the electrode, as describedhereinafter.

Each development electrode contains a pair of vacuum slots 103positioned on opposite sides of the entrance slot and parallel theretofor the removal of excess developer material from the development zone.The vacuum slots are suitably connected by a common vacuum line orconduit 1% as shown schematically in FIG. to a conventional dustcollector 165 which may, for example, comprise a blower connected to adust filter, preferably mounted externally of the machine.

For supporting the development electrode elements in the machine thereis provided a front rail mounting plate 111 and arear rail mountingplate 112 suitably attached to the main frame elements of the machinepreviously described.

Each development electrode .is supported for transverse movement bypairs of transverse rails 113. Each transverse rail is secured atopposite ends in an insulated rail brushing 114 mounted in a bushinghousing 115 secured to a rail mounting plate. For insulating theelectrodes from the frame of the machine there are provided insulatorwashers 116 held in place by adjusting screws 118 threaded throughinsulator screw bushings 117 posi tioned in suitable apertures in therail mounting plates.

For moving each development electrode from a first position or forwardposition, in which the electrode is in operative relation with respectto the drum, to the left as seen in FIG. 7, to a second position inwhich it is moved away from the drum or to the rear of the machine forthe purpose of cleaning the electrode, each developrnent electrode isconnected by a chain bracket 122 to a chain 123 which is driven eitherclockwise or counter-clockwise by an electrode clutch drive mechanismdescribed hereinafter. Bumpers 121 secured to the inner faces of thebushing housing limit the movement of the electrodes in eitherdirection.

The electrode clutch drive mechanism, for moving the developmentelectrodes, includes a pair of commercially available magnetic clutchesof conventional design for each development electrode; a clutch fordriving the electrode forward into its first portion or operativeposition and a clutch for driving the electrode back to its secondposition or purge position.

Referring specifically to FIGS. 6, 7 and 8, a pair of parallel shafts133, journaled in sleeve bearings 134 positioned in the angle brackets135 secured to mounting plate 128 suitably supported on the frame of themachine, are used to supply the input power of these clutches. Eachshaft 133 has fastened at an end thereof a gear 136 driven by motorMOT-3 through drive gear assembly 137 supported by the left-hand endangle bracket 135, as seen in FIG. 6, the shaft of motor MOT-3 beingconnected to the shaft of the drive gear assembly by coupling 138.

Although the clutches used to drive the development electrodes are acommon commercial type magnetic clutch, a brief description of theseclutches is deemed appropriate. As shown in FIG. 8, each clutch includesa stationary field 141 secured to an angle bracket 135. The rotorassembly 142' of each clutch is secured to a shaft 1 133 by a key 143for rotation therewith while the armature assembly 144- is positioned bya retainer ring 147 on splined armature hub 1*45 rotatably supportedwith respect to the shaft 133 by means of sleeve bearings 146. Theforward drive clutches are designated SC-7, SC-ll, SC-29, 80-441 andS051 and the back drive clutches are designated SC- d, S-C-19, 80-39,SC41 and SC-52 for moving electrodes -E-1, E-Z, E-3, E-4 and 5-5,respectively.

A ,gear 151 and a sprocket hub .152, fastened together by screws 153,are mounted on the splined armature subs of each of the clutches SC-7,SC-18, 80-29, SC- 40 and SC-51 and a gear 154 and .aplain hub 1155 aremounted on the splined armature hubs 145 of each of the clutchesSC-8,SC-19-, S060, 50-41 and 80-52. These assemblies are held in placeaxially at one end by set collars 156 and 156a, the other end of eachassembly riding against a thrust washer 157.

Each sprocket hub 152 has a chain 123 attached thereto, each chainpassing from a sprocket hub 152 up over a sprocket 1611 around asprocket 162 then parallel to the transverse rails 113 to and around asprocket 163 down over sprocket 164 back to thes-procket hub. Adevelopment electrode is connected to a chain intermediate sprockets 162and 163 by a bracket 122.

Each set of sprockets 161, 162, 16 3 and 164 are journaled in anopen-ended chain guard 165 suitably connected to a frame element of themachine as determined by the location of the development electrode whichit serves.

As the shafts 133 are rotated counterclockwise by motor MOT-3, therotors of the clutches will rotate with the shafts while the armatureassemblies of the clutches will remain stationary due to friction of theelements attached' thereto. As the field of a rear drive clutch isenergized, magnetic flux flows through the rotor, attracting thearmature assembly, the latter being driven by friction between these twoelements to rotate the gear 154 counterclockwise; gear 151 and thesprocket hub 152 of the associated forward drive clutch is caused tomove clockwise to move the associated development electrode to the rightas seen in FIG. 7. As the field of a rear drive clutch is de-energizedand the field of a forward drive clutch is energized, its armatureassembly and the gear 151 and-associated sprocket hub 1'52 thereon isdriven counterclockwise to drive the development electrode to the leftor first position. At the same time, the gear 151, of this forward driveclutch, which is rotating counterclockwise, drives the gear 154 of theassociated torward drive clutch clockwise, the latter being free torotate since it is not energized.

As described hereinafter, the operation of these clutches to efiectsequential movement of the development electrodes is controlled by aconventional motor driven electromechanical timer 3TR.

Powder Cloud Delivery and Purging System.

The powder cloud delivery and purging system of the apparatus isillustrated schematically in the pneumatic circuit diagram of FIG. 10,and a slightly more detailed schematic illustration of the pneumaticcircuit for the elements associated with a single development electrode,using the elements associated with development electrode E-l as anexample, is shown in FIGS. 9 and 9a.

Although any suitable powder cloud generator may be used, the powdercloud generators 171, used for each of the five development electrodes,are of the type disclosed in copending Huber application Serial No.19,845, new Patent No. 3,094,248, filed April 4, 1960. A powder cloudgenerator of this type is shown schematically only in FIGS. 9, 9a and10, since the details of the specific construction of a powder cloudgenerator is not deemed pertinent to the subject invention. For purposesof the present disclosure, it is deemed sufiicient to note that each ofthe powder cloud generators consists of a reservoir 183 whereindevelopment material is metered by at least one metering blade 184 ontoa rotating clothcovered disc 185 journaled for rotation within thereservoir. As the cloth-covered disc passes beneath a metering blade.184, a thin film of powder developing material is spread over thesurface of the cloth-covered disc.

The entire powder-cloud generator unit is pressurized so that as thedisc 135 passes beneath a pick-up tube or pick-up head 1-86, the thinlayer of metered powder on the disc is picked up by out-rushing air asit passes through the pick-up tube. Additional toner is continuouslydeposited on the disc 185 in front of the blade 184 from a suitabletoner dispenser 188. The disc 185 is mounted on a suitable shaftjournaled in the wall of the reservoir and is driven 'by a drive meansdescribed hereinafter.

During the powder cloud generating cycle pressurized aeriform fluid at apressure of approximately 20 pounds per square inch gauge is deliveredto the powder cloud generator from a suitable source, such as an aircompressor. The output 'from the powder cloud generator is controlled bya commercial type non-clogging valve, such as pinchvalve 172, controlledby suitable actuators, such as, for example, solenoids SOL-1t and SOL-11for the pinch valve controlling powder flow to development electrodeE-l.

From the powder cloud generator the powder cloud is delivered through apipe coupler 17 4 of the type disclosed in copending Burris et a1.application, Serial No. 742,372, filed June '16, 1958, now Patent2,965,136. The pipe coupling is used to permit the powder line from thepowder cloud generator to be coupled-through the ceramic needle 1% thedevelopment electrode or to permit the powder line from the powder cloudgenerator to be connected to the exhaust conduit of the system, and toperm-it a high-pressure air line to be connected to the developmentelectrode through the ceramic needle. As shown in FIGS. 9 and 9a, thefirst. element or the female coupling 174A of the pipe. coupler can beshifted actuator, such as the solenoids SOL-13 and SOL-14 rfordevelopment electrode E-l. The second elementor male coupling 17413 ofthe pipe coupler is driven into or out of engagement with the femalecoupling 174A by means of an air cylinder 175, the piston of which isconnected in a suitable manner to the male coupling 174B. Admission ofpressurized aeriform fluid to actuate the air cylinder .175 iscontrolled by a suitable coupler slide valve, such as by means of asolenoid-actuated valve SV-12 of conventional construction, in thepneumatic circuit for development electrode 154.

As shown in FIG. 9, which illustrates the position of the variouselements associated with development electrode E-l during thedevelopment cycle, the female coupler 174A, when shifted to the right,as seen in this figure, by actuation of solenoid SOL-l4, connects theconduit from the powder cloud generator 171 to the development electrodeE-l via the ceramic needle 192. The pinch valve 172 in this circuit ismaintained in an open position by actuation of solenoid SOL-1t duringthe development cycle to permit the how of the powder cloudtherethrough. The powder cloud in passing through the ceramic needle102, previously described, effects triboelectric charging of the powder.

To clean the development electrodes, the ceramic needle's, and thepowder-carrying conduits connecting these elements with the powder cloudgenerator, it is necessary to sequentially shift the developmentelectrodes to the rear of the machine so that clean air may be pulsedthrough these elements to purge them of developer powder. At the startof the purge cycle, the drive to the disc 1&5 of the powder cloudgenerator for the development electrode being withdrawn from itsoperating position is disengaged. The air cylinder 175 is actuated touncouple the male coupling 17413 from the female coupling 174A to permitthe latter to be shifted to the left as solenoid SOL-13 is energized,whereby the powder line from the powder cloud generator is in alignmentwith the exhaust conduit 104B and whereby a clean air conduit ispositioned in alignment with the conduit connected through the ceramicneedle in the development to either the right or left to align theconduit from the electrode. Then the air cylinder 175 is again actuatedthrough the solenoid controlled valve SV-lZ to couple the male coupling174B to the female coupling 174A.

Solenoid valve SV-lS is then energized to connect the powder cloudgenerator to the SO-pOund per square inch air line whereby high pressureair is delivered to the powder cloud generator. At the same timesolenoids SOL-10 and SOL-11 are sequentially energized to el fect thecyclic opening and closing of the pinch valve 172 to effect a pulsatingflow of air through the powder cloud generator and through the powderline, whereby the pick-up tube of the powder cloud generator and thepowder line are cleaned. Powder cleaned from the pick-up tube 186 andfrom the powder line is delivered through exhaust conduit 1043 to aconventional dust collector positioned externally of the machine. At thesame time the line connected via the ceramic needle 102 in thedevelopment electrode is connected to the l00-pound per square inch linethrough the pipecoupler 174 and the solenoidactuated ceramic needlepurge valve SV-l7 in the 100- pound pressure line is. sequentiallyenergized and then de-energized whereby this valve is rapidly opened andclosed, causing the high pressure clean air to be pulsed through theceramic needle and the development electrode. Simultaneously, thedevelopment electrode is connected directly to a branch of the IOU-poundper square inch line through an electrode purge valve, herein shown as asolenoid-actuated valve SV-16 for development electrode E4, which iscyclicly energized to cause a pulsating flow of air through thedevelopment electrode.

' The development electrode during the purging operaion is positioned atthe rear of the machine and under a dust hood 1322, described indetail'hereinafter, connected to the'dust collector 105 by a conduit104A.

As previously described, the purging of a development electrode and itsassociated elements with clean high pressure air occurs when thedevelopment electrode is in the purge position, that is, away from thexerographic drum, the remaining development electrodes of thesystembeing in their first position or forward position whereby theelectrostatic latent image 1011 the drum is at all times being developedby the equivalent of four'development electrodes, as shown in the timingchart of 'FIGS. 12 and 12a.

The powder cloud generators for each of the development electrodes aredriven independently of each other by means of suitable electricclutches. As shown in FIGS.72 and 3, the output shaft of each clutchhasa gear 192. mounted thereon which meshes with a driven gear 1% on theshaft 187 of .a powder cloud generator. The input shaft of each clutchis connected to a motor MOT-11 driven shaft 194 bygears 19:5 and 196mounted on the input shafts of theclutchesand on the shaft 194,respectively. The shaft 194 is suitably .journaled and operativelyconnected to motor MOT:11 by belt 197 en circling pulleys 198 mountedon'the end ofshaft 194 and the shaft of the motor MOT-11. Each of theclutches driving the powder cloud generators 171 is a conventionalmagnetic clutch designated as clutches SC9, SC-20, SC-31, SC42. andSC-53 in the electrical circuit for driving the. powder cloud generators171 delivering a powder cloud to development electrodes E-LE-Z, 13-3,13-4 and E-S, respectively.

Since it is not deemed necessary to show the actual details or locationof the common hardware usedin the pneumatic circuit of the apparatus,these elements are only shown schematically in FIGS. 9, 9a and -10. Asshown, the 50, 20 and IOU-pound per square inch air lines, previouslydescribed, are preferably connected y a common intake line to a suitablesource of pressurized aeriform fluid, such as a commercial compressorlocated ex-- ternally of the machine. The pressure tothe -50-poundpressure line is controlled by a pressure regulator valve 201 and thepressure to the 20-pound line is controlled by a pressureregulatingvalve 203. A solenoid-controlled main air valve SV-l is positioned inthe 20-.pound line to control the flow of air to the normally closedsolenoidoperated generator pressure valves SV-15, SV-26, SV-37, SV-dSand SV-59.

The generator pressure valves EV-26, SV-34, SV-48 and SV-59 controllingthe air flow to the powder cloud generators that service the developmentelectrodes E-2, E-3, E4 and E-S, respectively, are solenoid-operatedvalves like the generator pressure valve SV-iS, previously described.

A-suitable check valve'2tl4 and a manually operated shut-oh valve 295are interposed between each of the generator pressure valves and theirrespective powder cloud generators. The shut-off valves'2ti5areinstalled in the conduit to the powder cloud generators to permit theoperator to shut off the flow of pressurized 'aeriform fluid to theseunits as desired.

To bleed aeriform fluid from the powder cloud generators,solenoid-operated blow down valves SKI-62, SV-63, SV64, SV65 and SV-66are mounted in the line connecting the powder cloud generators to acommon exhaust conduit 134.

Flow of aeriform fluid to the remaining air cylinders "175 associatedwith development electrodes E 2, E-S,

E4 and E 5 is controlled by coupler slide valves SV-ZS, SV-34, SV-45 andSV56,respectively. The ceramic needle purge valves SV-Zii, SV-39, SV-St)and SV-61 are used to control the flow of clean pressurized aeriformfluid through the ceramic needles in development electrodes E-2, E45,13-4 and E-S, respectively. Electrode purge valves SV-27, SV-38, SV-Mand SV-60 are used 19 to control the flow of clean pressurized aeriformfluid to development electrodes E-2, E-3, 13-4 and 15-5, respectively.

The coupler slide valves SV-IZ, SV-23, SV-34, SV-45 and SV-55, and thevalve SV-6 controlling the flow-of air to air cylinders and 48,respectively, are conventional three-way valves to permit pressurizedaeriform fluid to flow'to the aircylinders from the lOO-pound pressureline and to exhaust the expanded aen'form fluid from the air cylindersvia a common exhaust conduit 207.

The actuation of'the pinch valves 172 and the shifting of the femalecoupling 174A of pipe coupler 174 are effected. by means of :a :pair ofsolenoids associated with each of these elements. The operation of thepinch valves 172' is effected by the following pairs .of solenoids:SOLJO, SOL-11; SOL-21, SOL-22; SOL-32, SOL-33; SOL-43, SOL-44; andSOL-54, SOL-55. The shifting of the female couplings 174A iseffected bythe following pairs of solenoids: SOL13,tSOL-14; SOL-24, SOL-25; SOL-35,SOL-36; SOL-46, SOL-47; and SOL-57, SOL- 58. Each of the above-describedsets of solenoids are given in theorder of their relationship to thedevelopment electrodes E-1,E-2, E-3, E-4, and E-5, respectively.

To remove developer powder particles from the dust hoods 182 each hoodis connected to the inlet of a blower 208, the outlet of each'blowerbeing connected to a commom-vacuum conduit 104a. In the apparatus shown,each blower is driven by a separate motor, the motors being designatedas MOT-12, MOT-13, MOT-14, MOT-15, and MOT-16 in the electrical circuitfor the dust hoods for development electrodes 13-1, 13-2, E-3, E4, andE-5, respectively.

Transfer Mechanism In the transfer station, the powder image developedon the xerographic drum is transferred to a web of support material, inthis case a plastic-coated paper, by means of electrostatic imagetransfer. In this process, the web of support material is brought intocontact with the drum, and an electric field applied to the back of thesupport material causes the powder particles to adhere to the supportmaterial. The charge deposited on the paper is generated by a pair ofhigh voltage corona generating devices 15a similar to the coronagenerating device previously described.

As shown, a web of support material 250 moves from a supply roll 251around an idler roll 252, contacting the drum under the pair of highvoltage corona generating devices 15, then around a second idler roll252, up over a third idler roll 252, across to and around heat fuser253, down behind a'viewing platen such as glass plate'254, under anidler roll 252, to be wound up on the take-up spool 255.

The fuser 253 consists of a suitable resistor R-l heated platen which ismaintained by a suitable thermoswitch THS-I described hereinafter, at aconstant fusing temperature to fuse the powder images onto the web ofsupport material to form a permanent image.

A tension and tension control mechanism similar to that previouslydescribed for the film handling system is used to ensure adequatetension on the support web to permit the Web to be advanced byfrictional contact with the drum to insure synchronous movement of theweb and drum. Since the:mounting of the supply roll 251, idler rolls 252and take-up spool 255, and the braking mechanism and drive mechanism forthe supply roll 251 and takeeup spool 255, respectively, aresubstantially similar to the equivalentelements of the film handlingsystem and since the specific details of these elements form no part ofthe subject invention they are not described or illustrated in detailherein.

However, to permit a clearer understanding of the operation of theapparatus, the electrical control elements of the support web handlingmechanism are shown in FIG. 11.

The web supply roll is connected to a hysteresis brake 1 l SB-2 (notshown) similar to brake 83-4 and the power to the brake 33-2 iscontrolled by a Variac T-l in the same manner as power to brake SB-d iscontrolled by Variac T-3 in the film handling system.

The web take-up spool 255 is driven by a motor MOT1 through a hysteresisclutch SC-3 similar to clutch SC-S, and the power to clutch 50-3 iscontrolled by Variac T-Z, in the same manner as power to clutch SC-S iscontrolled by Variac T-d in the film handling system.

Drum Cleaning'and Discharge To remove residual particles of developermaterial remaining on the drum after image transfer, there is provided apair of drum cleaning mechanisms 270 and 271, each comprising a pair ofrotatable brushes 272 of such construction as to apply extremely lightpressure to the photoconductive surface of the xerographic plate todislodge any particles of developer material that may adhere thereto.Each pair of brushes, journaled in a dust collector chamber 273connected to mounting plate 8, are rotated by means of belts 273encircling pulleys 276 connected to the brushes and motors, in thedirections shown in ,FIG. 2 to fan air upward from the drum between thebrushes. The rotation of the brushes causes a pumping action, forcingair and particles of developer material removed from the drum into thedust collector chamber from where it is exhausted through vacuum conduit104 to the dust collector 105.

The brushes of drum cleaning mechanisms 270 and 271 are driven by motorsMOT5 and MOT-6, respectively.

Positioned next to the second drum cleaning unit 271 is a discharge lampassembly 275 having a light source LMP-3 therein to flood the surface ofthe drum with light to dissipate any residual electrostatic chargeremaining on the drum.

Machine Operation A clearer understanding of the operation of thexerographic reproducing machine of the subject invention can best beobtained by reference to the schematic wiring diagram of the machine,the sequence of operation chart and the following description.

Before starting the machine, a web of film or other copy containingimages to be reproduced, and a supply of support material onto which thereproduced images are to be transferred are placed on the respectivesupply rolls and threaded around the film handling mechanisms and thesupport material handling mechanisms, respectively, as previouslydescribed. The powder cloud generators are charged with a supply ofdeveloper material before pressurized aeriform fluid is delivered to thegenerators.

The air compressor or other source of pressurized aeriform fluidconnected to the pneumatic system of the machine, and the dust collectorare preferably not an integral part of the machine but separateelementsoperated independently of the control circuit of the xerographicapparatus. 7 Their operation is not described in detail herein except tonote that they must be in operation before the xerographic process isinitiated.

The first operationron starting the xerographic machine is for theoperator to press the start button or Power-On switch SW-ll. SwitchSW-1is a single throw, two pole switch which connects the apparatus to asource of electrical power, such as a commercial 235-volt 60-cycleoutlet. v

Upon closure of switch SW-Il, electrical power flows through normallyclosed thermostat THS-1 to control relay ICR to effect closure of itsnormally open contact ECRA connected in series with the resistor R4. ofthe fuse-r. Indicator lamp LMP-ll connected inrparallel with resistorR-1 is energized when power is supplied to the fuser through contactICRA as a visual indication to the operator that the fuser is inoperation. While switch SW-l remains closed, the thermostat TI-IS-l willcontinue to control the energization of the resistor R4 through thecontrol relay ICR. v i

Power is also applied to a conventional voltage stabilizer unitdesignated T-5 for high voltage power supply for transfer PS-l and thehigh voltage power supply for charging PS-Z, and to the regulated powersupply and current stabilizer chassi described in detail hereinafter.Power is transmitted to the conventional voltage power supplies PS-l andPS2 at this time to permit the filaments of these units to heat.Normally closed contact 3TR-l will also energize the motor MOT-3TR for asequenceof-events timer 3TR.

The sequence-of-events timer STR and the purge cycling timer 4TR arewell known conventional type electrical mechanical timers which includeone or more cams positioned on a rotatable shaft to actuate switches toclose their contacts, the angular displacement of the risers on thecarns and the location of the switches being readily determined inaccordance with the desired actuation time of these switches asdetermined by the sequence of operation chart. 7

The shaft of timer STR and the shaft of timer iTR, not shown, arerotated at predetermined speeds by suitable constant speed motors suchas motors MOT-3TR and motor MOT-4TR, respectively. Since the specificdetailed configuration of the cams and the switches actuated thereby donot form a part of this invention, the timers 3TR and 4TR are not shownor described in detail, it being deemed sufficient only to illustratethe contacts of the switches schematically in the electrical circuitdiagram, and the time sequence of operation of these switches in thesequence of operation chart.

Referring again to the operation of motor MOT-3T1}, this motor willoperate to reset timer contact 3TR-1, that is, it will operate until allof the contacts 3TR-2 to 3TR- 31, inclusive, of the timer are closed atwhich time contact 3TR-1 is opened to de-energize this motor. Althoughcontacts 3TR2 to 3TR+31, inclusive, are closed during the reset cycle ofthe timer, they do not affect the operation of other elements in thecircuit since the electrical conductive lines to these elementscontrolled by the timer are de-energized during this period.

Next the print-run switch SW-2 is momentarily closed by the operator tothereby energize control relay ZCR, closing its holding contact 2CR1. Atthe same time, control 'relay 3CR is energized through normally closedcontact ZTR-l of the end-of-operation timer ZTR. As control relay 3CR isenergized, its contacts 3CR-1, 3CR-2, 3CR-3, and 3CR-4 are closed. Ascontact 3CR3 is closed, control relay GCR is energized to close itscontact 6CR-1 which together with closed contacts 3CR-1 and ZCR-l form aholding circuit whereby the operator may release the print-run switchSW-Z.

Power is also transmitted through the closed contact 3CR-3 through thevariable resistor R-lZ to the high voltage power supply PS-1 to apply ascreen potential to the corona generating devices 15a. The coronagenerating devices 15a may be energized at this time even though thexerographic drum is not rotating because the sheet of support materialinterposed between the transfer scorotron and the drum will protect thephotoconductive surface of the Xerographic drum.

Solenoids SOL-14, SOL-25, SOL-36, SOL-47, and SOL-58 are energized toshift the male couplers 174A to the right as seen in the pneumaticcircuit diagram in position to connect the powder; lines from the powdercloud generators to their respective development electrodes. normallyclosed contact 3TR-6B, 3TR-12B, STR-ISB, 3TR-24B, and 3TR-30B,respectively as power is supplied to this portion of the circuit throughclosed contact 3CR-4.

Also as contact SCR-4 is closed, the solenoid-operated coupler slidevalves SV-lZ, SV-23, SV34, SV-45 and SV-S are energized through closedcontacts EaTR-S, ftTR-ll, 3TR-17, 3T 3, and 3TR-29, respectively, to

effect operation of the air cylinders to couple the male These solenoidsare energized through the

1. A XEROGRAPHIC CONTACT PRINTING APPARATUS INCLUDING A XEROGRAPHICPLATE MOUNTED FOR ROTATION, DRIVE MEANS CONNECTED TO SAID XEROGRAPHICPLATE FOR ROTATING SAID XEROGRAPHIC PLATE AT A PREDETERMINED SPEED,CHARGING MEANS POSITIONED IN CLOSELY SPACED RELATION TO SAID XEROGRPHICPLATE TO PLACE AN ELECTROSTATIC CHARGE THEREON, CONTROL MEANS CONNECTEDTO SAID CHARGING MEANS TO VARY THE ELECTROSTATIC CHARGE APPIED TO SAIDXEROGRAPHIC PLATE, A FILM SUPPLY SPOOL, A FILM TAKE-UP SPOOL TO RECEIVEFILM FROM SAID SUPPLY SPOOL, A FIRST FILM POSITIONING ROLL AND A SECONDFILM POSITIONING ROLL MOUNTED IN SPACED RELATION TO EACH OTHER ADJACENTSAID XEROGRAPHIC PLATE, AT LEAST ONE OF SAID FILM POSITIONING ROLLSBEING MOUNTED FOR MOVEMENT FROM A FIRST POSITION IN WHICH A FILM MAY BEINSERTED BETWEEN SAID FILM POSITIONING ROLL AND SAID XEROGRAPHIC PLATETO A SECOND POSITION IN WHICH SAID FILM POSITIONING ROLL IS IN PRESSURECONTACT WITH SAID XEROGRAPHIC PLATE WITH A DILM SANDWICHED INBETWEEN, AFIRST TENSIONING MEANS CONNECTED TO SAID FILM SUPPLY SPOOL AND A SECONDTENSIONING MEANS CONNECTED TO SAID TAKE-UP SPOOL FOR MAINTAINING A WEBOF FILM IN FRICTIONAL CONTACT WITH XEROGRAPHIC PLATE OVER A PORTIONTHEREOF FOR SYNCHRONOUS MOVEMENT WITH SAID XEROGRAPHIC PLATE, PROJECTORMEANS POSITIONED ADJACENT SAID XEROGRAPHIC PLATE, SAID PROJECTOR MEANSINCLUDING A LIGHT SOURCE, A LIGHT DISCHARGE TUBE POSITIONED BETWEEN SAIDFIRST FILM POSITIONING ROLL AND SAID SECOND FILM POSITIONING ROLLWHEREBY LIGHT FROM SAID LIGHT SOURCE PROJECTED THROUGH SAID LIGHTDISCHARGE TUBE IS DIRECTED ONTO A FILM WHILE IN CONTACT WITH SAIDXEROGRAPHIC PLATE TO FORM AN ELCTROSTATIC LATENT INMAGE ON SAIDXEROGRAPHIC PLATE, MEANS CONNECTED TO SAID LIGHT DISCHARGE TUBE TO VARYTHE AMOUNT OF RADIATION PROJECTED THROUGH THE FILM ONTO SAID XEROGRAPHICPLATE, DEVELOPING MEANS INCLUDING DEVELOPMENT ELECTRODE MEANS POSITIONEDADJACENT SAID XEROGRAPHIC PLATE FOR DEVELOPING AN ELCTROSTATIC LATENTIMAGE THEREON, AND POWER MEANS CONNECTED TO SAID DEVELOPMENT ELECTRODEMEANS TO APPLY A CONTROLLED BIAS POTENTIAL TO SAID DEVELOPMENT ELECTRODEMEANS.